Two-phase thermal syphon assembly

ABSTRACT

A two-phase thermal syphon assembly includes a plate and one or more thermal syphon pipes. The plate is configured to extract heat from one or more heat-generating devices in contact therewith. The plate has surfaces that define a volume thereof. The surfaces include a first flat surface, a second flat surface that extends in a horizontal plane parallel to a plane in which the first flat surface extends, and one or more side surfaces extending between the first and second flat surfaces. The side surfaces have a distance between the first and second flat surfaces that is less than distances on the first flat surface between the side surfaces and distances on the second flat surface between the side surfaces. Each of the flat surfaces is configured to respectively contact one of the heat-generating devices to extract heat therefrom.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 62/868,043, filed Jun. 28, 2019, which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to thermal syphon pipes used to provide cooling in industrial applications and, more particularly, to a two-phase thermal syphon assembly for cooling power modules.

BACKGROUND OF THE INVENTION

Conventional solutions for cooling wind turbine power modules have several drawbacks. For example, the liquid cooling of these power modules is known to consume a significant amount of energy produced by the wind turbine. This reduces the amount of wind power that can be sold. Further, many of the components in conventional wind turbine power convertor cooling systems are known to be prone to failure, thereby necessitating excess repair costs and additional overhead required to monitor the wind turbines for failures. In addition, many liquid cold plates of current wind turbine liquid cooling systems incorporate the use of ethylene glycol therein. Ethylene glycol is toxic and has been known to leak from liquid cooling circuits contained within the cold plates, thus creating a negative environmental impact on a power source that is partially implements due to its environmental friendliness.

As such, there is a desire in the wind power industry to repower existing wind turbines. The repowering of wind turbines includes, but is not limited to, the replacement of components that are costly to operate for reasons delineated above with components utilizing new technologies that are more dependable and more efficient and have less of a negative impact on the environment.

Two-phase thermal syphon assemblies have conventionally been used for cooling purposes. A two-phase thermal syphon assembly is a passive heat exchanger that can cool a power source by transferring heat generated by the power source into a surrounding cooling medium, such as air. Such an assembly may have a cooling plate that can extract heat from a power source that is in contact with the cooling plate.

The assembly may also have a plurality of thermal syphon pipes in contact with the cooling plate that can transfer the heat extracted via natural convection from the power source by the cooling plate into a surrounding cooling medium. The thermal syphon pipes do this using liquid-to-vapor phase changes.

Each of the thermal syphon pipes includes a working fluid, such as water, sealed in a long thin walled cavity under vacuum. The cavity may be cylindrical or rectangular, but is not limited thereto. A portion of the cavity is attached to or embedded within the cooling plate. When the heat is applied to a portion of the thermal syphon pipes from the cooling plate, the working fluid boils and is converted into vapor.

The vapor moves from the heated portion, or an evaporating area, of the thermal syphon pipes to a lower temperature area, or a condensing area, of the thermal syphon pipes via an adiabatic portion of the thermal syphon pipes where no phase change takes place. The lower temperature area of the thermal syphon pipes is at an opposite end of the thermal syphon pipes from the end of the thermal syphon pipes in contact with the cooling plate. In the lower temperature area of the thermal syphon pipes, the vapor will condense back into a liquid. The liquid will move back to the heated area of the thermal syphon pipes via the adiabatic portion of the thermal syphon pipes to be heated and evaporated again. Thus, a two-phase flow cycle is created.

The condensed liquid moves from the lower temperature area of the thermal syphon pipes to the heated area of the thermal syphon pipes using gravity. The thermal syphon pipes must be oriented in such a way that gravity can draw the condensed liquid down toward the heated portion of the thermal syphon pipes.

For example, such an orientation may include a thermal syphon pipe being angled downwardly from the lower temperature area of the thermal syphon pipe to the heated area of the thermal syphon pipe. This allows gravity to draw the condensed liquid from the higher, condensing area of the thermal syphon pipe toward the lower, evaporating area of the thermal syphon pipe.

A large fin stack is positioned around the lower temperature area, and possibly the adiabatic portion, of the thermal syphon pipe. The fin stack can transfer the heat away from the thermal syphon pipes into the air through forced or natural convection.

Specifically, as previously noted, two-phase thermal syphon assemblies that utilize thermal syphon pipes require gravity to transfer heat from a cooling plate. For example, in some two-phase thermal syphon assemblies, 8° of inclination is required to be observed between a thermal syphon pipe and a horizontal plane. The gravity component drives the condensed liquid in the condensing area back to the evaporating area, where it is evaporated again and rises against the gravity as vapor to the condenser area of the thermal syphon pipe.

However, many wind turbine power sources are horizontally oriented, and, as such, must be cooled using a horizontal cooling plate. This inhibits the use of conventional two-phase thermal syphon assemblies to cool such wind turbine power sources, as the cooling plates thereof are positioned in vertical planes for gravity purposes.

The present invention has been developed to address these and other issues by providing a new cooling design for a two-phase thermal syphon assembly that can be applied horizontally to cool horizontally oriented power supplies, such as those used in wind turbines.

SUMMARY OF THE INVENTION

In one example embodiment of the present invention, a two-phase syphon assembly includes a plate and one or more thermal syphon pipes. The plate is configured to extract heat from one or more heat-generating devices in contact therewith. The plate has surfaces that define a volume thereof and one or more channels formed within the volume. The surfaces include a first flat surface, a second flat surface, and one or more side surfaces extending between the first and second flat surfaces. The first and second flat surfaces are perpendicular to a gravity vector. Each of the flat surfaces are configured to respectively contact one of the heat-generating devices to extract heat therefrom. The channels are respectively open at the side surfaces and extend from the side surfaces through the volume of the plate toward the gravity vector at an angle between 0° to 4° from the first and second flat surfaces to positions within the volume at which the channels respectively end.

The thermal syphon pipes are respectively embedded within the channels and extend out of and away from the channels. The thermal syphon pipes are configured to remove the extracted heat from the plate.

In another example embodiment of the present invention, a two-phase syphon assembly includes a plate and one or more thermal syphon pipes. The plate is configured to extract heat from one or more heat-generating devices in contact therewith. The plate has surfaces that define a volume thereof and one or more channels formed within the volume. The surfaces include a first flat surface, a second flat surface, and one or more side surfaces extending between the first and second flat surfaces. The first and second flat surfaces are parallel to a gravity vector. Each of the flat surfaces are configured to respectively contact one of the heat-generating devices to extract heat therefrom. The channels are respectively open at the side surfaces and extend from the side surfaces through the volume of the plate toward the gravity vector to positions within the volume at which the channels respectively end.

The thermal syphon pipes are respectively embedded within the channels and extend out of and away from the channels. The thermal syphon pipes are configured to remove the extracted heat from the plate.

Other features and aspects may be apparent from the following detailed description, the drawings and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in the specification and illustrated in the accompanying drawings which form a part hereof, and wherein:

FIG. 1 is a top view illustrating a first embodiment of a two-phase thermal syphon assembly of the present invention;

FIG. 2 is a sectional view illustrating a section 2-2′ from FIG. 1 of the first embodiment of the two-phase thermal syphon assembly of the present invention;

FIG. 3 is a top view illustrating a second embodiment of the two-phase thermal syphon assembly of the present invention;

FIG. 4 is a sectional view illustrating a section 4-4′ from FIG. 3 of the second embodiment of the two-phase thermal syphon assembly of the present invention;

FIG. 5 is a sectional view illustrating a third embodiment of a two-phase thermal syphon assembly of the present invention, where the section illustrated corresponds with section 2-2′ from FIG. 4 with an orientation and features that are structurally unique from FIG. 4;

FIG. 6 is a graphical illustration of cooling performance of the two-phase thermal syphon of the present invention relative to an angle at which the thermal syphon pipes of the two-phase thermal syphon are oriented and an amount of power generated by heat-generating devices being cooled by the two-phase thermal syphon; and

FIG. 7 is a tabular illustration of the data graphically illustrated in FIG. 6 that is related to the cooling performance of the two-phase thermal syphon of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

For the purposes of this discussion, it is noted that thermal syphon pipes may differ from certain conventional heat pipes, as certain conventional heat pipes may have wicking that lines the inner surfaces of the heat pipes. The inner surfaces of the thermal syphon pipes are typically understood not to have wicking. However, embodiments disclosed herein are not limited thereto, as the invention disclosed herein may conceivably be performed with thermal syphon pipes having inner surface lined with wicking. In addition, while helical structures may be used within the thermal syphon pipes for purposes such as wicking, embodiments disclosed herein are not limited thereto, as the internal volume of the thermal syphon pipes may be void apart from the working fluid contained therein, which is described in greater detail below.

In addition, for the purposes of this discussion, a gravity vector V_(G) extends in a direction that corresponds with a direction in which a force dictated by the laws of gravity extends.

Referring now to the drawings, wherein the showing is for illustrating a preferred embodiment of the invention only and not for limiting same, the invention will be described with reference to FIGS. 1-7. The structural orientation of the embodiments of the invention, although not provided to limit the same, will be described with reference to FIGS. 1-5.

FIGS. 1 and 2 illustrate a two-phase thermal syphon assembly 100 in accordance with a first embodiment of the present invention. The assembly 100 includes a plate 2 and thermal syphon pipes 4. The plate 2 extracts heat from heat-generating devices 10 in contact therewith. While the heat-generating devices 10 are illustrated as being fastened to a first flat surface 11 of the plate 2, which is more fully described below, the heat-generating devices 10 may also be fastened to a second flat surface 12 of the plate 2, which is also more fully described below.

The plate 2 may be made of metal or any material known by one having ordinary skill in the art to extract heat from one of the heat-generating devices 10 described herein. The heat-generating devices 10 from which heat is extracted by the plate 2 could be any device known by one having ordinary skill in the art to generate heat, including, but not limited to, inverters, semiconductors, microprocessors, and power supplies or sources.

The plate 2 has surfaces that define a volume thereof. The surfaces of the plate 2 include a first flat surface 11 and a second flat surface 12 that extends along a plane p2 that is parallel to a plane p1 along which the first flat surface 11 extends. The first and second flat surfaces 11 and 12 are both perpendicular to the gravity vector V_(G).

The surfaces of the plate 2 also include side surfaces 13 that extend between the first flat surface 11 and the second flat surface 12. The side surfaces 13 may have a distance t1 between the first flat surface 11 and the second flat surface 12 that is less than distances t2 and t3 on the first flat surface 11 between the side surfaces 13. The distance t1 between the first flat surface 11 and the second flat surface 12 is also less than distances t2 and t3 on the second flat surface 12 between the side surfaces 13. The side surfaces 13 may be parallel with the gravity vector V_(G), but embodiments described herein are not limited thereto.

Each of the flat surfaces 11 and 12 may be in contact with a heat-generating device 10 to extract heat therefrom. While each of the flat surfaces 11 and 12 is capable of being in contact with and extracting heat from multiple heat-generating devices, the plate 2 illustrated in FIGS. 1 and 2 is in contact with a single heat-generating device 10. In the case of FIGS. 1 and 2, the plate 2 is mounted on the heat-generating device 10 at the first flat surface 11. However, embodiments defined herein are not limited thereto. For example, another heat-generating device 10 may be mounted on the second flat surface 12.

The plate 2 also has channels 8 that are formed within the volume of the plate 2. The channels 8 are respectively open at the side surfaces 13 and respectively extend from the side surfaces 13 through the volume of the plate 2 toward the gravity vector V_(G) at an angle θ1 between 0° to 4° from the first and second flat surfaces 11 and 12 to positions within the volume at which the channels 8 respectively end.

In addition, while the plate 2 may be mounted on the heat-generating device 10 through any number of mounting means known to one having ordinary skill in the art, FIGS. 1 and 2 illustrate the plate 2 as being fastened to the heat-generating device 10 by fasteners 1. The fasteners 1 could be any fixing element known to one having ordinary skill in the art to be appropriate for such applications, such as, but not limited to, bolts, screws, or pins.

The thermal syphon pipes 4 remove the extracted heat from the plate 2, which serves to cool the plate 2 that has extracted heat from the heat-generating device 10. The thermal syphon pipes 4 respectively include first straight portions 14 and second straight portions 15. The first straight portions 14 respectively include first ends 17 of the thermal syphon pipes 4 embedded within the channels 8 from the ends of the channels 8 to the openings of the channels 8 in the side surfaces 13. The second straight portions 15 respectively have second ends 18 of the thermal syphon pipes 4 that extend away from the plate 2 and the openings of the channels 8 in the side surfaces 13.

The thermal syphon pipes 4 extend through the channels 8. The first straight portions 14 of the thermal syphon pipes 4 respectively extend from the first ends 17 of the thermal syphon pipes 4 through the channels 8 formed within the plate 2 and exit the plate 2 through the side surfaces 13 to extend toward connection with the second straight portions 15. The first straight portions 14 may be completely embedded in the channels 8 of the plate 2 up until transition points 19 of the thermal syphon pipes 4 at which the first straight portions 14 of the thermal syphon pipes 4 connect with other portions of the thermal syphon pipes 4. As such, the first straight portions 14 of the thermal syphon pipes 4 respectively extend along planes p3 that are at the angle θ1 between 0° to 4° from the planes p1 and p2 along which the first flat surface 11 and the second flat surface 12 respectively extend.

In one example, the assembly 100 also includes a stack 6 of fins 7 through which the second straight portions 15 respectively extend to the second ends 18 of the thermal syphon pipes 4. The fins 7 are configured to cool the thermal syphon pipes 4. The second straight portions 15 of the thermal syphon pipes 4 extend in planes p4 that are angled to the planes p1 and p2 along which the first and second flat surfaces 11 and 12 extend. For example, an angle θ2 of planes p4 may increase at the transition point 19 from the angle θ1 between 0° to 4° to be 8° from the planes p1 and p2. However, while 8° may be optimal for angle θ2, embodiments described herein are not limited thereto. For example, angle θ2 may be any angle known to one having ordinary skill in the art to promote optimal operation of two-phase thermal syphon assemblies. The second straight portions 15 also may respectively extend away from the first straight portions 14 in planes p4 that are at an angle that is greater than angle θ1.

In another example, the assembly 100 may include a fin stack enclosure 9 that is configured to enclose the stack 6 of fins 7. The fin stack enclosure 9 is primarily enabled to assist in the cooling of the fins 7 that have received the extracted heat from the plate 2 that was transferred to the thermal syphon pipes 4. One or more fans 3 may be positioned within or outside the fin stack enclosure 9. The fans 3 are operative to cool the fins 7. The fans 3 are powered by a power supply 5. The power supply 5 can be any such device known by one having ordinary skill in the art to be acceptable to power the fans 3.

A working fluid is contained within the thermal syphon pipes 4. The working fluid is configured to evaporate when exposed to the extracted heat from the plate 2 that has been transferred to the working fluid through the thermal syphon pipes 4. The working fluid condenses because of the cooling of the thermal syphon pipes 4 provided by the fins 7. The working fluid may be water or methanol, but is not limited thereto, and may be any type of fluid known to one having ordinary skill in the art to be effective for use in cooling applications.

In one example, as previously noted, the thermal syphon pipes 4 respectively have transition points 19 at which the first straight portions 14 of the thermal syphon pipes 4 connect with other portions of the thermal syphon pipes 4. In first types of the thermal syphon pipes 4, the first straight portions 14 are respectively directly connected to the second straight portions 15 at the transition points 19. In second types of the thermal syphon pipes 4, the first straight portions 14 are respectively connected to the second straight portions 15 of the second types of the thermal syphon pipes 4 through angular portions 16 of the second types of the thermal syphon pipes 4 that are connected to the first straight portions 14 of the second types of the thermal syphon pipes 4 at the transition points 19. The transition points 19 in the first types of the thermal syphon pipes 4 are at a same location along the first types of the thermal syphon pipes 4 as are the transition points 19 in the second types of the thermal syphon pipes 4.

The angular portions 16 of the second types of thermal syphon pipes 4 extend away from the first straight portions 14 of the second types of thermal syphon pipes 4 at an angle that is greater than an angle at which the second straight portions 15 of the first types of thermal syphon pipes 4 extend away from the first straight portions 14 of the first types of thermal syphon pipes 4. In addition, as previously noted, the first straight portions 14 of the first and second types of thermal syphon pipes 4 may be completely embedded in the channels 8 of the plate 2 up until the transition points 19 of the first and second types of thermal syphon pipes 4.

In another example, a sum of the distance t1 of the side surfaces 13 between the first and second flat surfaces 11 and 12 and respective outside diameters of embedded portions of the first straight portions 14 that are embedded in the plate 2 is in a range of 3.5% to 9.0% of respective lengths L1 of the embedded portions. If the plate 2 is rectangular, the lengths L1 of the embedded portions are respectively greater than or equal to 80% of the distance t3 on the first or the second flat surfaces 11 and 12 that extends from one of the side surfaces 13 into which the embedded portions are inserted to an opposite one of the side surfaces 13.

FIGS. 3 and 4 illustrate a two-phase thermal syphon assembly 300 in accordance with a second embodiment of the present invention. It is noted that, while assembly 300 substantially corresponds with assembly 100, there are differences between assembly 100 and assembly 300. In assembly 300, heat-generating devices 33 and 40 are respectively mounted on the first and second flat surfaces 33 and 40. The thermal syphon pipes 34 of the assembly 300 are greater in number and feature a greater variety of angular portion 46 orientations than the thermal syphon pipes 4 of the assembly 100. As will be described below, while fans are not illustrated in FIG. 3, one having ordinary skill in the are would clearly foresee the application of fans for cooling within the enclosure 39, which is mentioned below.

The assembly 300 includes a plate 32 and thermal syphon pipes 34. The plate 32 extracts heat from heat-generating devices 33 and 40 in respective contact with first and second flat surfaces 41 and 42. The plate 32 may be made of metal or any material known by one having ordinary skill in the art to extract heat from one of the heat-generating devices 33 and 40 described herein. The heat-generating devices 33 and 40 from which heat is extracted by the plate 32 could be any devices known by one having ordinary skill in the art to generate heat, including, but not limited to, inverters, semiconductors, microprocessors, and power supplies or sources.

The plate 32 has surfaces that define a volume thereof. The surfaces of the plate 32 include a first flat surface 41 and a second flat surface 42 that extends along a plane p6 that is parallel to a plane p5 along which the first flat surface 41 extends. The first and second flat surfaces 41 and 42 are both perpendicular to the gravity vector V_(G).

The surfaces of the plate 32 also include side surfaces 43 that extend between the first flat surface 41 and the second flat surface 42. The side surfaces 43 have a distance t4 between the first flat surface 41 and the second flat surface 42 that is less than distances t5 and t6 on the first flat surface 41 between the side surfaces 43. The distance t4 between the first flat surface 41 and the second flat surface 42 is also less than distances t5 and t6 on the second flat surface 42 between the side surfaces 43. The side surfaces 43 may be parallel with the gravity vector V_(G), but embodiments described herein are not limited thereto.

The flat surfaces 41 and 42 are respectively in contact with heat-generating devices 33 and 40 to extract heat therefrom. In the case of FIGS. 3 and 4, the plate 32 is fixed on the heat-generating device 33 at the first flat surface 41 and the heat-generating device 40 at the second flat surface 42.

The plate 32 also has channels 38 that are formed within the volume of the plate 32. The channels 38 are respectively open at the side surfaces 43 and respectively extend from the side surfaces 43 through the volume of the plate 32 toward the gravity vector V_(G) at an angle θ3 between 0° to 4° from the first and second flat surfaces 41 and 42 to positions within the volume at which the channels 38 respectively end.

In addition, while the plate 32 may be fixed to the heat-generating devices 33 and 40 through any number of mounting means known to one having ordinary skill in the art, FIGS. 3 and 4 illustrate the plate 32 as being fastened to the heat-generating device 33 and 40 through fasteners 31. The fasteners 31 could be any fixing element known to one having ordinary skill in the art to be appropriate for such applications, such as, but not limited to, bolts, screws, or pins.

The thermal syphon pipes 34 remove the extracted heat from the plate 2, which serves to cool the plate 2 that has extracted heat from the heat-generating devices 33 and 40. The thermal syphon pipes 34 respectively include first straight portions 44 and second straight portions 45. The first straight portions 44 respectively include first ends 47 of the thermal syphon pipes 34 embedded within the channels 38 to the openings of the channels 38 in the side surfaces 43. The second straight portions 45 respectively have second ends 48 of the thermal syphon pipes 34 that extend away from the plate 32 and the openings of the channels 38 in the side surface 43.

In the assembly 300, more thermal syphon pipes 34 are required for cooling of the plate 32. This is because two heat-generating device 33 and 40 rely on the plate 32 for cooling. As such, the plate 32 requires more cooling than would have been the case in the first embodiment when only one heat-generating device 10 is being cooled by the plate 2. For purposes of example, it can be assumed that the power dissipation each of the heat-generating devices 33 and 40 is the same as the power dissipation of the heat-generating device 10. Thus, the power dissipation extracted by the plate 32 would be double of that which would be extracted by the plate 2. Additional thermal syphon pipes 34 serve to address the need for the more rapid cooling of the plate 32 in such a situation.

The thermal syphon pipes 34 extend through the channels 38. The first straight portions 44 of the thermal syphon pipes 34 respectively extend from the first ends 47 of the thermal syphon pipes 34 through the channels 38 formed within the plate 32 and exit the plate 32 through the side surfaces 43 to extend toward connection with the second straight portions 45. The first straight portions 44 may be completely embedded in the channels 38 of the plate 32 up until transition points 49 of the thermal syphon pipes 34 at which the first straight portions 44 of the thermal syphon pipes 34 connect with other portions of the thermal syphon pipes 34. As such, the first straight portions 44 of the thermal syphon pipes 34 respectively extend along planes p7 that are at an angle θ3 between 0° to 4° from the planes p5 and p6 along which the first flat surface 41 and the second flat surface 42 respectively extend.

In one example, the assembly 300 also includes a stack 36 of fins 37 through which the second straight portions 45 respectively extend to the second ends 48 of the thermal syphon pipes 34. The fins 37 are configured to cool the thermal syphon pipes 34. The second straight portions 45 of the thermal syphon pipes 34 extend in planes p8 that are angled to the planes p5 and p6 along which the first and second flat surfaces 41 and 42 extend. For example, an angle θ4 of planes p8 may increase at the transition point 49 from the angle between 0° to 4° to be 8° from the planes p5 and p6. However, while 8° may be optimal for angle θ4, embodiments described herein are not limited thereto. For example, angle θ4 may be any angle known to one having ordinary skill in the art to promote optimal operation of two-phase thermal syphon assemblies. The second straight portions 45 also may respectively extend away from the first straight portions 44 in planes p8 that are at an angle that is greater than angle θ3.

In another example, the assembly 300 may include a fin stack enclosure 39 that is configured to enclose the stack 36 of fins 37. The fin stack enclosure 39 is primarily enabled to assist in the cooling of the fins 37 that have received the extracted heat from the plate 32 that was transferred to the thermal syphon pipes 34. While not illustrated in FIGS. 3 and 4, just as in the first embodiment, one or more fans may be positioned within or outside the fin stack enclosure 39.

A working fluid is contained within the thermal syphon pipes 34. The working fluid is configured to evaporate when exposed to the extracted heat from the plate 32 that has been transferred to the working fluid through the thermal syphon pipes 34. The working fluid condenses because of the cooling of the thermal syphon pipes 34 provided by the fins 37. The working fluid may be water or methanol, but is not limited thereto, and may be any type of fluid known to one having ordinary skill in the art to be effective for use in cooling applications.

In one example, as previously noted, the thermal syphon pipes 34 respectively have transition points 49 at which the first straight portions 44 of the thermal syphon pipes 34 connect with other portions of the thermal syphon pipes 34. In first types of the thermal syphon pipes 34, the first straight portions 44 are respectively directly connected to the second straight portions 45 at the transition points 49. In second types of the thermal syphon pipes 34, the first straight portions 34 are respectively connected to the second straight portions 45 of the second types of the thermal syphon pipes 34 through angular portions 46 of the second types of the thermal syphon pipes 34 that are connected to the first straight portions 44 of the second types of the thermal syphon pipes 34 at the transition points 49. The transition points 49 in the first types of the thermal syphon pipes 34 are at a same location along the first types of the thermal syphon pipes 34 as are the transition points 49 in the second types of the thermal syphon pipes 34.

The angular portions 46 of the second types of thermal syphon pipes 34 extend away from the first straight portions 44 of the second types of thermal syphon pipes 34 at an angle that is greater than an angle at which the second straight portions 45 of the first types of thermal syphon pipes 34 extend away from the first straight portions 44 of the first types of thermal syphon pipes 34. In addition, as previously noted, the first straight portions 44 of the first and second types of thermal syphon pipes 34 may be completely embedded in the channels 38 of the plate 32 up until the transition points 49 of the first and second types of thermal syphon pipes 34.

In contrast with FIGS. 1 and 2, the embodiments illustrated in FIGS. 3 and 4 show angular portions 46 having angles that differ from other angular portions 46. This design accommodates the additional thermal syphon pipes 34 required in order to adequately cool the plate 32. It also enables the second straight portions 45 to be positioned in different locations of the fin stack 36 for optimal cooling and configuration of the thermal syphon pipes 34 within the fin stack 36.

In another example, a sum of the distance t4 of the side surfaces 43 between the first and second flat surfaces 41 and 42 and respective outside diameters of embedded portions of the first straight portions 44 that are embedded in the plate 32 is in a range of 3.5% to 9.0% of respective lengths L2 of the embedded portions. If the plate 32 is rectangular, the lengths L2 of the embedded portions are respectively greater than or equal to 80% of the distance t6 on the first or the second flat surfaces 41 and 42 that extends from one of the side surfaces 43 into which the embedded portions are inserted to an opposite one of the side surfaces 43.

It is additionally noted that, if not previously discussed, the angle at which the channels 8, 38 are oriented and the thermal syphon pipes 4 and 34 respectively extend through the plates 2 and 32 from planes p1, p2 and p3, p4 necessarily serve to affect the distances t1 and t4 between the first flat surfaces 11 and 41 and the second flat surfaces 12 and 42. For example, if the thermal syphon pipes 4 and 34 and the channels 8 and 38 were to be angled through the plates 2 and 32 at 4° instead of 3°, to maintain the same coverage of the heat-generating devices 10 and 33, 40 on the plates 2 and 32, the distances t1 and t4 would have to be comparatively increased.

FIG. 5 illustrates a two-phase thermal assembly 700 in accordance with a third embodiment of the present invention. It is noted that, while assembly 700 substantially corresponds with assembly 300, there are differences between assembly 300 and assembly 700. In assembly 300, the first and second flat surfaces 41 and 42 are both perpendicular to the gravity vector V_(G). In assembly 700, the first and second flat surfaces 81 and 82 are both parallel to the gravity vector V_(G). In addition, in assembly 300, the channels 38 are respectively open at the side surfaces 43 and respectively extend from the side surfaces 43 through the volume of the plate 32 toward the gravity vector V_(G) at an angle θ3 between 0° to 4° from the first and second flat surfaces 41 and 42 to positions within the volume at which the channels 38 respectively end. In assembly 700, the channels 78 are respectively open at the side surfaces 83 and respectively extend from the side surfaces 83 through the volume of the plate 72 parallel to the gravity vector V_(G) and the first and second flat surfaces 81 and 82 to positions within the volume at which the channels 78 respectively end.

The assembly 700 includes a plate 72 and thermal syphon pipes 74. The plate 72 extracts heat from heat-generating devices 73 and 80 in respective contact with first and second flat surfaces 81 and 82. The plate 72 may be made of metal or any material known by one having ordinary skill in the art to extract heat from one of the heat-generating devices 73 and 80 described herein. The heat-generating devices 73 and 80 from which heat is extracted by the plate 72 could be any device known by one having ordinary skill in the art to generate heat, including, but not limited to, inverters, semiconductors, microprocessors, and power supplies or sources.

The plate 72 has surfaces that define a volume thereof. The surfaces of the plate 72 include a first flat surface 81 and a second flat surface 82 that extends along a plane p10 that is parallel to a plane p9 along which the first flat surface 81 extends. The first and second flat surfaces 81 and 82 are both parallel to the gravity vector V_(G).

The surfaces of the plate 72 also include side surfaces 83 that extend between the first flat surface 81 and the second flat surface 82. As is illustrated in FIG. 5, the first and second flat surfaces 81 and 82 are additionally oriented around 90° from a horizontal plane. It is noted that the distances on the first flat surfaces 81 between the side surfaces 83 is substantially like the distances t5 and t6 illustrated with respect to assembly 300 in FIG. 3. It is also noted that the distances on the second flat surface 82 between the side surfaces 83 are substantially like the distances t5 and t6 illustrated with respect to the assembly 300 illustrated in FIG. 3. As such, the side surfaces 83 have a distance t7 between the first flat surface 81 and the second flat surface 82 that is less than distances on the first flat surface 81 between the side surfaces 83 that correspond with the distances t5 and t6 on the first flat surface 41 between the side surfaces 43. In addition, the distance t7 between the first flat surface 81 and the second flat surface 82 is also less than distances on the second flat surface 82 between the side surfaces 83 that correspond with the distances t5 and t6 on the second flat surface 42 between the side surfaces 43.

As in the assembly 300, the flat surfaces 81 and 82 are respectively in contact with heat-generating devices 80 and 73 to extract heat therefrom. The heat-generating device 80 is fixed to the plate 72 at the first flat surface 81. The heat-generating device 73 is mounted on the second flat surface 82.

The plate 72 also has channels 78 that are formed within the volume of the plate 72. The channels 78 are respectively open at the side surfaces 83 and respectively extend from the side surfaces 83 through the volume of the plate 72 in a direction parallel to the gravity vector V_(G) to positions within the volume at which the channels 78 respectively end.

In addition, while the plate 72 may be fixed to the heat-generating devices 73 and 80 through any number of mounting means known to one having ordinary skill in the art, FIG. 5 illustrates the plate 72 as being fastened to the heat-generating device 73 and 80 through fasteners 71. The fasteners 71 could be any fixing element known to one having ordinary skill in the art to be appropriate for such applications, such as, but not limited to, bolts, screws, or pins.

The thermal syphon pipes 74 remove the extracted heat from the plate 72, which serves to cool the plate 72 that has extracted heat from the heat-generating devices 73 and 80. The thermal syphon pipes 74 respectively include first straight portions 84 and second straight portions 85. The first straight portions 84 respectively include first ends 87 of the thermal syphon pipes 74 embedded within the channels 78 to the openings of the channels 78 in the side surfaces 83. The second straight portions 85 respectively have second ends 88 of the thermal syphon pipes 74 that extend away from the plate 72 and the openings of the channels 78 in the side surface 83.

The thermal syphon pipes 74 extend through the channels 78. The first straight portions 84 of the thermal syphon pipes 74 respectively extend from the first ends 87 of the thermal syphon pipes 74 through the channels 78 formed within the plate 72 and exit the plate 72 through the side surfaces 83 to extend toward connection with the second straight portions 85. The first straight portions 84 may be completely embedded in the channels 78 of the plate 72 up until transition points 89 of the thermal syphon pipes 74 at which the first straight portions 84 of the thermal syphon pipes 74 connect with other portions of the thermal syphon pipes 74. As such, the first straight portions 84 of the thermal syphon pipes 74 respectively extend along planes p11 that are parallel with the planes p9 and p10 and the gravity vector V_(G) along which the first flat surface 81 and the second flat surface 82 respectively extend.

In one example, the assembly 700 also includes a stack 76 of fins 77 through which the second straight portions 85 respectively extend to the second ends 88 of the thermal syphon pipes 74. The fins 77 are configured to cool the thermal syphon pipes 74. The second straight portions 85 of the thermal syphon pipes 74 extend in planes p12 that are angled to the planes p9 and p10 along which the first and second flat surfaces 81 and 82 extend. For example, an angle θ6 of planes p12 may be 8° from the planes p9 and p10. However, while 8° may be optimal for angle θ6, embodiments described herein are not limited thereto. For example, angle θ6 may be any angle known to one having ordinary skill in the art to promote optimal operation of two-phase thermal syphon assemblies.

In another example, the assembly 700 may include a fin stack enclosure 79 that is configured to enclose the stack 76 of fins 77. The fin stack enclosure 79 is primarily enabled to assist in the cooling of the fins 77 that have received the extracted heat from the plate 72 that was transferred to the thermal syphon pipes 74. While not illustrated in FIG. 5, just as in the first embodiment, one or more fans may be positioned within or outside the fin stack enclosure 79.

A working fluid is contained within the thermal syphon pipes 74. The working fluid is configured to evaporate when exposed to the extracted heat from the plate 72 that has been transferred to the working fluid through the thermal syphon pipes 74. The working fluid condenses because of the cooling of the thermal syphon pipes 74 provided by the fins 77. The working fluid may be water or methanol, but is not limited thereto, and may be any type of fluid known to one having ordinary skill in the art to be effective for use in cooling applications.

In one example, the thermal syphon pipes 74 respectively have transition points 89 at which the first straight portions 84 of the thermal syphon pipes 74 connect with other portions of the thermal syphon pipes 74. In first types of the thermal syphon pipes 74, the first straight portions 84 are respectively directly connected to the second straight portions 85 at the transition points 89. In second types of the thermal syphon pipes 74, the first straight portions 84 are respectively connected to the second straight portions 85 of the second types of the thermal syphon pipes 74 through angular portions 86 of the second types of the thermal syphon pipes 74 that are connected to the first straight portions 84 of the second types of the thermal syphon pipes 74 at the transition points 89. The transition points 89 in the first types of the thermal syphon pipes 74 are at a same location along the first types of the thermal syphon pipes 74 as are the transition points 89 in the second types of the thermal syphon pipes 74.

The angular portions 86 of the second types of thermal syphon pipes 74 extend away from the first straight portions 84 of the second types of thermal syphon pipes 74 at an angle that is greater than an angle at which the second straight portions 85 of the first types of thermal syphon pipes 74 extend away from the first straight portions 84 of the first types of thermal syphon pipes 74. In addition, as previously noted, the first straight portions 84 of the first and second types of thermal syphon pipes 74 may be completely embedded in the channels 78 of the plate 72 up until the transition points 89 of the first and second types of thermal syphon pipes 74.

In another example, a sum of the distance t7 of the side surfaces 83 between the first and second flat surfaces 81 and 82 and respective outside diameters of embedded portions of the first straight portions 84 that are embedded in the plate 74 is in a range of 3.5% to 9.0% of respective lengths L3 of the embedded portions. If the plate 74 is rectangular, the lengths L3 of the embedded portions are respectively greater than or equal to 80% of a distance on the first or the second flat surfaces 81 and 82 that extends from one of the side surfaces 83 into which the embedded portions are inserted to an opposite one of the side surfaces 83. In this case, the distance on the first or the second flat surfaces 81 and 82 that extends from one of the side surfaces 83 into which the embedded portions are inserted to an opposite one of the side surfaces 83 corresponds with the distance t3 illustrated in FIG. 1 and the distance t6 illustrated in FIG. 3.

It is foreseen that the assembly 100 would be installed in applications in which it is required that a temperature rise in the respective heat-generating devices 10 and 80 is 50° C. or less when the respective heat-generating devices 10 and 80 are operating at 1100 W, thereby requiring a power dissipation of at least 1100 W by the assembly 100. It is foreseen that the assemblies 300 and 700 would be installed in application in which it is required that a temperature rise in each of the heat-generating devices 33 and 40 is 50° C. or less when each of the respective heat-generating devices 33, 73 and 40, 80 are operating at 1100 W, thereby requiring a power dissipation of at least 2200 W by the assemblies 300 and 700. As an additional note, an embodiment is fully foreseeable in which respective heat-generating devices 33, 73 and 40, 83 of the assemblies 300 and 700 would each operate at 550 W, thereby requiring the power dissipation of at least 1100 W, similar to that of the heat-generating device 10.

FIGS. 6 and 7 illustrate cooling performance of the two-phase thermal syphon of the present invention relative to an angle at which thermal syphon pipes of the two-phase thermal syphon are oriented and an amount of power generated by heat-generating devices being cooled by the two-phase thermal syphon.

The cooling performance data was obtained utilizing the assembly 300 in conjunction with platforms that enabled the incline of the first and second flat surfaces 41 and 42 at −3°, −2°, −1°, 0°, 1°, and 87° angles from the horizontal. The thermal syphon pipes 34 were oriented to extend through the channels 38 of the plate 32 toward the gravity vector V_(G) in the plane p7 at an angle of 3° from the first and second flat surfaces 41 and 42 to positions within the volume at which the channels 38 respectively end. This provided tests in which the thermal syphon pipes 34 were respectively oriented at 0°, 1°, 2°, 3°, 4°, and 90° angles from the horizontal with the objective being to study the temperature rise of the assembly 300 for different power dissipation levels at those pipe orientations. It is noted that, even though the incline of the first and second flat surfaces 41 and 42 is at an 87° angle from the horizontal, the testing of the thermal syphon pipes 34 at a 90° angle from the horizontal directly corresponds with the assembly 700, at which the thermal syphon pipes 74 are also at a 90° angle from the horizontal and extend in a direction parallel to the gravity vector V_(G).

The platforms served to support the assembly 300 with the heat-generating devices 33 and 40 being mounted on and supported by the plate 32. The heat-generating devices 33 and 40 of the assembly 300 each began operation at 550 W. As such, the base power dissipation required was the same as the heat-generating device 10 if operating at 1100 W. The heat-generating devices 33 and 40 used during testing were heater blocks. Water was charged to the thermal syphon pipes 34 as the working fluid.

The tests were conducted keeping in mind that, for typical power electronics applications, the maximum temperature rise on the plate 32 of the assembly 300 should be 50° C. If the temperature rises on the plate 32 above 50° C., the thermal syphon pipes 34 are no longer able to adequately cool the plate 32. To study the efficacy of the pipe orientations and test the limits thereof, the maximum amount of power applied for dissipation was 3200 W, and the maximum temperature on the plate 32 of the assembly 300 could rise to 90° C. Thermocouples were positioned to extend through the heat-generating devices 33 and 40 (heater blocks) to contact the plate 32 in order to measure the temperature of the plate 32 in various locations. The ambient temperature in the area surrounding the assembly 300 was controlled to be between 23° C. and 25° C. and was monitored by thermocouples. A wind tunnel was used to cool the fins 37. The wind tunnel utilized the fin stack enclosure 39 along with cooling devices such as the fans 3 and the fan power supply 5 provided in the assembly 100 and illustrated in FIG. 1.

It is noted that, although the cooling performance data was obtained using the arrangement described above, any of the embodiments described herein may yield cooling performance data corresponding therewith. For example, in each case, the angle of the thermal syphon pipe to the horizontal is being manipulated. As such, regardless of the orientation of the thermal syphon pipes through the plates, the performance of the thermal syphon pipes can be adjusted through positioning the thermal syphon pipes at appropriate angles from the horizontal.

In view of this, FIGS. 6 and 7 will now be used to explain the results of the cooling performance test. For purposes of this disclosure, DT represents the average temperature of the plate 32 across all the thermocouple readings. Each orientation may result in varying temperatures at different locations within the plate 32. Keeping this in mind, the stability of temperature increases in all the locations throughout the plate 32 is generally signified by an absence of precipitous increases in DT. While the temperature readings taken by the thermocouples at separate locations across the plate 32 increase commensurate with an increase in power needing to be dissipated, a steady increase in DT generally signifies that DT is not increasing as a result of precipitous elevations in temperature at specific locations within the plate 32. On the other hand, precipitous increases in DT generally signifies that certain locations of the plate 32 are experiencing precipitous surges in temperature that the cooling of the thermal syphon pipes 34 is not able to adequately address. Such precipitous increases will eventually lead to dry out of the thermal syphon pipes 34 responsible for cooling the locations experiencing such surges.

In addition, the timing in the disclosure below is measured from the time the initial power is applied to the plate 32. Specific power levels were maintained for a time as it was determined whether the DT would be steady over a period. As previously alluded to, a failure of the DT to remain steady over a period for a specific power amount suggested that the assembly 300 in the specific orientation was unable to effectively dissipate the power amount applied to the plate 32, thereby causing uncontrollable, precipitous escalation of DT and leading to likely dry out.

When the thermal syphon pipes 34 were oriented at 0° from the horizontal and perpendicular to the gravity vector V_(G), at a power dissipation requirement of 1100 W (100% of the power that the assembly 300 was designed to dissipate), the DT became steady between 23° C. and 24° C. after about 10 minutes from the application of power to the plate 32. After about 25 minutes of total exposure to 100% of the design, the power dissipation requirement was increased to 125% of the design at 1375 W. At this power, DT exhibited instability and steadily increased to about 31° C. at the end of 65 total minutes, leading to the assumption that the thermal syphon pipes 34 were struggling to effectively cool the plate 32. When the power dissipation requirement was set to 140% of the design at 1575 W after about 65 total minutes through about 100 total minutes, DT did not stabilize and continued to rise to about 43° C. at 100 total minutes of exposure, thereby evidencing that the thermal syphon pipes 34 in this orientation were unable to effectively cool the plate 32. Further, when the power dissipation requirement was set to 160% of the design at 1780 W after about 150 total minutes, DT continued to precipitously increase to about 70° C. at the end of about 210 minutes and did not stabilize, leading to the presumption that the assembly 300 had failed.

As such, taking into account the data illustrated in FIG. 6, when the thermal syphon pipes 34 were oriented at 0° from the horizontal and perpendicular to the gravity vector V_(G), the assembly 300 was able to meet design requirements, as, after about 10 minutes, the DT was steady between 23° C. and 24° C. However, this orientation was never able to maintain DT at a steady state at a power above 100% of the design. While the state of DT at 125% of the design was only mildly unstable, this still shows that the orientation could not be depended upon to effectively cool the plate 32 in a repeatable manner when power dissipation requirements are over 100% of the design at 1100 W.

When the thermal syphon pipes 34 were oriented at 1° from the horizontal and 89° from the gravity vector V_(G), at a power dissipation requirement of 1100 W, DT became steady between 25° C. and 26° C. within about 10 minutes of application of power to the plate 32. After about 25 minutes of total exposure to 100% of the design, the power dissipation requirement was increased to 125% of the design at 1375 W. As a result, at about 30 total minutes of exposure, DT became steady between 30° C. and 31° C. When the power dissipation requirement was set to 140% of the design at 1575 W at about 40 total minutes of exposure, DT became steady at about 34° C. at around 45 total minutes of exposure. When the power dissipation requirement was set to 160% of the design at 1780 W at about 80 minutes of total exposure, DT became somewhat steady between 40° C. and 41° C. at around 85 minutes of total exposure. However, there were noticeable fluctuations and instabilities in the DT during this time between 85 minutes of total exposure and about 100 minutes of total exposure, leading to the assumption that the thermal syphon pipes 34 were struggling to effectively cool the plate 32. The power dissipation requirement was then set to 170% of the design at 1880 W at about 100 minutes of total exposure. This caused the DT to steadily increase to between 44° C. and 45° C. without stabilization until about 125 minutes of total exposure. At 125 minutes of total exposure, the power dissipation requirement was set to 180% of the design at 2000 W. The DT at this power dissipation requirement continued the steady increase to between 47° C. and 48° C. at about 150 minutes of total exposure. At this point, the power dissipation requirement was set to 190% of the design at 2100 W. The DT subsequently and precipitously increased to about 51° C., which is over the maximum DT that is allowable, after about 175 minutes of total exposure. Stability of the DT at this power dissipation requirement became noticeably poorer. After 175 minutes of total exposure, the power dissipation requirement was set to 200% of the design at 2200 W. At this point, the DT did not stabilize, leading to the presumption that the assembly 300 had failed.

As such, taking into account the data illustrated in FIG. 6, when the thermal syphon pipes 34 were oriented at 1° from the horizontal and 89° from the gravity vector V_(G), the assembly 300 was able to meet design requirements, as, after about 10 minutes, the DT was steady between 25° C. and 26° C. However, this orientation was never able to maintain DT at a steady state at a power at or above 160% of the design. While the state of DT at 160% of the design was only somewhat unstable, this still shows that the orientation could not be depended upon to effectively cool the plate 32 in a repeatable manner when power dissipation requirements are greater than or equal to 160% of the design at 1780 W.

Thus, the orientation in which the thermal syphon pipes 34 of the assembly 300 is oriented at 1° from the horizontal and 89° from the gravity vector V_(G) is a viable option if it can be determined that the power dissipation will not reach above 140% of the design. While the DT remained within the acceptable level up to 180% of the design in the test, the unstable trend of the DT at power above 140% of the design precipitous upward trend of the DT at power above 180% of the design makes this orientation unpredictable and unreliable above 140% of the design.

When the thermal syphon pipes 34 were oriented at 2° from the horizontal and 88° from the gravity vector V_(G), when at the design power of 1100 W, DT stabilized between 26° C. and 27° C. in about 10 minutes of total exposure. When the power dissipation requirement was increased to 125% of the design at 1375 W at around 20 minutes of total exposure, DT stabilized between 31° C. and 32° C. at about 25 minutes of total exposure. When the power dissipation requirement was set to 140% of the design at 1575 W, at about 50 minutes of total exposure, DT stabilized between 37° C. and 38° C. at about 55 minutes of total exposure. When the power dissipation requirement was set to 160% of the design at 1780 W at about 75 minutes of total exposure, DT generally stabilized between 41° C. and 42° C. at about 80 minutes of total exposure. When the power dissipation requirement was set to 170% of the design at 1880 W at about 90 minutes of exposure, DT generally stabilized between 43° C. and 44° C. at about 100 minutes of total exposure. When the power dissipation requirement was set to 180% of the design at 2000 W at about 110 minutes of total exposure, DT stabilized at about 48° C. at about 120 minutes of total exposure. When the power dissipation requirement was set to 190% of the design at 2100 W at about 130 minutes of total exposure, DT stabilized at about 49° C. at about 135 minutes of total exposure. When the power dissipation requirement was set to 200% of the design at 2200 W at about 150 minutes of total exposure, DT stabilized between 51° C. and 52° C. at about 155 minutes after total exposure, which is over the maximum DT that is allowable.

As such, taking into account the data illustrated in FIG. 6, when the thermal syphon pipes 34 were oriented at 2° from the horizontal and 88° from the gravity vector V_(G), the assembly 300 was able to meet design requirements, as, in about 10 minutes of total exposure, the DT was steady between 26° C. and 27° C. The DT was generally able to stabilize in response to increases in design power up to 200% of the design, at which point the DT rose above the maximum DT of 50° C. Thus, the orientation in which the thermal syphon pipes 34 of the assembly 300 are oriented at 2° from the horizontal and 88° from the gravity vector V_(G) is a viable option if it can be determined that the power dissipation will not reach above 200% of the design.

When the thermal syphon pipes 34 were oriented at 3° from the horizontal and 87° from the gravity vector V_(G), when at the design power of 1100 W, DT stabilized between 26° C. and 27° C. in about 5 minutes of total exposure. When the power dissipation requirement was increased to 125% of the design at 1375 W at around 20 minutes of total exposure, DT stabilized between 31° C. and 32° C. at about 30 minutes of total exposure. When the power dissipation requirement was increased to 140% of the design at 1575 W at about 35 minutes of total exposure, DT stabilized between 36° C. and 37° C. at about 40 minutes of total exposure. When the power dissipation requirement was increased to 160% of the design at 1780 W at about 45 minutes of total exposure, DT stabilized at about 42° C. at about 50 minutes of total exposure. When the power dissipation requirement was increased to 170% of the design at 1880 W at about 70 minutes of total exposure, DT stabilized between 44° C. and 45° C. at about 75 minutes of total exposure. When the power dissipation requirement was set to 180% of the design at 2000 W, DT increased to about 48° C. When the power dissipation requirement was set to 190% of the design at 2100 W at about 85 minutes of total exposure, DT stabilized at about 51° C. after about 90 minutes of total exposure, which is over the maximum DT that is allowable.

As such, taking into account the data illustrated in FIG. 6, when the thermal syphon pipes 34 were oriented at 3° from the horizontal and 87° from the gravity vector V_(G), the assembly 300 was able to meet design requirements, as, in about 8 minutes of total exposure, the DT was steady between 26° C. and 27° C. The DT was generally able to stabilize in response to increases in design power up to 190% of the design, at which point DT rose above the maximum DT of 50° C. In fact, even despite the lower temperatures observed with the 2° orientation, the 3° orientation yielded results that were steadier than the 2° orientation in a quicker timeframe. In addition, the temperature in the adiabatic areas of testing environment was more stable at the 3° orientation than at the 2° orientation.

Thus, the orientation in which the thermal syphon pipes 34 of the assembly 300 are oriented at 3° from the horizontal and 87° from the gravity vector V_(G) is a viable option if it can be determined that the power dissipation will not reach above 190% of the design. The increased steadiness of the 3° orientation may encourage selection of the 3° orientation when a small distance t1 is not critical to the application, as the 3° orientation would require an increased distance t4 of the side surface 43 of the plate 32 as compared with the 2° orientation.

When the thermal syphon pipes 34 were oriented at 4° from the horizontal and 86° from the gravity vector V_(G), when at the design power of 1100 W, DT stabilized at about 27° C. in about 5 minutes of total exposure. When the power dissipation requirement was set to 125% of the design at 1375 W at about 15 minutes of total exposure, DT stabilized at about 33° C. in about 20 minutes of total exposure. When the power dissipation requirement was set to 140% of the design at 1575 W at about 30 minutes of total exposure, DT stabilized between 37° C. and 38° C. in about 35 minutes of total exposure. When the power dissipation requirement was set to 160% of the design at 1780 W at about 40 minutes of total exposure, DT stabilized between 42° C. and 43° C. in about 50 minutes of total exposure. When the power dissipation requirement was set to 170% of the design at 1880 W at about 60 minutes of total exposure, DT stabilized at about 45° C. in about 65 minutes of total exposure. When the power dissipation requirement was set to 180% of the design at 2000 W at about 70 minutes of total exposure, DT stabilized between 47° C. and 48° C. in about 75 minutes of total exposure. When the power dissipation requirement was set to 190% of the design at 2100 W at about 85 minutes of total exposure, DT stabilized at about 51° C. in about 90 minutes of total exposure, which is over the maximum DT that is allowable.

As such, taking into account the data illustrated in FIG. 6, when the thermal syphon pipes 34 were oriented at 4° from the horizontal and 86° from the gravity vector V_(G), the assembly 300 was able to meet design requirements, as, in about 5 minutes of total exposure, the DT was steady at about 27° C. The DT was generable to stabilize in response to increases in design power up to 190% of the design, at which point DT rose above the maximum DT of 50° C. In fact, even despite the lower temperatures observed with the 2° orientation, the 4° orientation yielded results that were steadier than the 2° orientation.

Thus, the orientation in which the thermal syphon pipes 34 of the assembly 300 are oriented at 4° from the horizontal and 86° from the gravity vector V_(G) is a viable option if it can be determined that the power dissipation will not reach above 190% of the design. However, it is noted that there was no substantial improvement with the 4° orientation over the 3° orientation. This is significant because the 4° orientation would require an increased distance t4 over the 3° orientation.

When the thermal syphon pipes 34 were oriented at 90° from the horizontal and parallel to the gravity vector V_(G), when at the design power of 1100 W, DT was steady at about 24° C. in about 10 minutes of total exposure. When the power dissipation requirement was set to 125% of the design at 1375 W at about 30 minutes of total exposure, DT stabilized at about 30° C. in about 35 minutes of total exposure. When the power dissipation requirement was set to 140% of the design at 1575 W at about 55 minutes of total exposure, DT stabilized at about 35° C. in about 60 minutes of total exposure. When the power dissipation requirement was set to 160% of the design at 1780 W at about 85 minutes of total exposure, DT stabilized between 39° C. and 40° C. at 90 minutes of total exposure. When the power dissipation stabilized at about 42° C. in 90 minutes of total exposure. When the power dissipation requirement was set to 180% of the design at 2000 W at about 150 minutes of total exposure, DT stabilized between 44° C. and 45° C. in about 155 minutes of total exposure. When the power dissipation requirement was set to 190% of the design at 2100 W at about 175 minutes of total exposure, DT stabilized between 46° C. and 47° C. in about 180 minutes of total exposure. When the power dissipation requirement was set to 200% of the design at 2200 W at about 200 minutes of total exposure, DT stabilized at about 49° C. in about 205 minutes of total exposure. When the power dissipation requirement was set to 210% of the design at 2300 W at about 225 minutes of total exposure, DT stabilized between 51° C. and 52° C. in about 230 minutes of total exposure, which is over the maximum DT that is allowable.

As such, taking into account the data illustrated in FIG. 6, when the thermal syphon pipes 34 were oriented at 90° from the horizontal and parallel to the gravity vector V_(G), the assembly 300 was able to meet design requirements, as, in about 10 minutes of total exposure, the DT was steady at about 24° C. The DT generally was able to stabilize in response to increases in design power up to 200% of the design, at which point the DT rose above the maximum DT of 50° C. Thus, the orientation in which the thermal syphon pipes 34 of the assembly 300 are oriented at 90° from the horizontal and parallel to the gravity vector V_(G) is a viable option if it can be determined that the power dissipation will not reach above 200% of the design.

However, it is noted that the plate 32 in the 90° orientation would not be applicable to heat-generating devices that are required to support the plate 32. This would include the heat-generating devices in the assemblies 100 and 300 illustrated in FIGS. 2 and 4, as the respective heat-generating devices 10 and 33, 40 extend in planes that are perpendicular to the gravity vector V_(G). On the other hand, the heat-generating devices 73 and 80 of the assembly 700 extend parallel to the gravity vector V_(G). The 90° orientation would be optimal to cool vertically oriented heat-generating devices 73 and 80 if enough room was located in a plane parallel to the gravity vector V_(G) and extending above the plate 32.

The foregoing descriptions regard specific embodiments of the present invention. It should be appreciated that this embodiment is described for purposes of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof. 

Having described the invention, the following is claimed:
 1. A two-phase thermal syphon assembly, comprising: a plate configured to extract heat from one or more heat-generating devices in contact therewith, the plate having surfaces that define a volume thereof and one or more channels formed within the volume, the surfaces including a first flat surface, a second flat surface, and one or more side surfaces extending between the first and second flat surfaces, the first and second flat surfaces being perpendicular to a gravity vector, each of the flat surfaces being configured to respectively contact one of the heat-generating devices to extract heat therefrom, the channels being respectively open at the side surfaces and extending from the side surfaces through the volume of the plate toward the gravity vector at an angle between 0° to 4° from the first and second flat surfaces to positions within the volume at which the channels respectively end; and one or more thermal syphon pipes respectively embedded within the channels and extending out of and away from the channels, the thermal syphon pipes being configured to remove the extracted heat from the plate.
 2. The assembly of claim 1, wherein the second flat surface extends along a plane that is parallel to a plane along which the first flat surface extends
 3. The assembly of claim 2, wherein the side surfaces have a distance between the first and second flat surfaces that is less than distances on the first flat surface between the side surfaces and distances on the second flat surfaces between the side surfaces.
 4. The assembly of claim 1, wherein the first flat surface is mounted on top of one of the heat-generating devices in contact therewith.
 5. The assembly of claim 2, wherein the thermal syphon pipes include first and second straight portions, the first straight portions respectively including first ends of the thermal syphon pipes, the second straight portions respectively including second ends of the thermal syphon pipes, the first ends of the thermal syphon pipes being respectively embedded in the channels.
 6. The assembly of claim 5, wherein the first straight portion of the thermal syphon pipes respectively extend along planes that are at an angle between 0° to 4° from the planes along which the first and second flat surfaces extend.
 7. The assembly of claim 5, wherein the first straight portions of the thermal syphon pipes respectively extend from the first ends of the heat pipes through the channels and exit the plate through the side surfaces to extend toward connection with the second straight portions.
 8. The assembly of claim 5, further comprising: a stack of fins through which the second straight portions respectively extend to the second ends of the thermal syphon pipes, the fins being configured to cool the thermal syphon pipes, wherein the second straight portions of the thermal syphon pipes extend through the fins in planes that are angled to the planes along which the first and the second flat surfaces extend.
 9. The assembly of claim 8, wherein a working fluid is contained within the thermal syphon pipes, the fluid being configured to evaporate when exposed to the extracted heat from the plate that has been transferred to the working fluid through the thermal syphon pipes, the working fluid being further configured to condense as a result of the cooling of the thermal syphon pipes provided by the fins.
 10. The assembly of claim 5, wherein the thermal syphon pipes respectively have transition points at which the first straight portions of the thermal syphon pipes connect with other portions of the thermal syphon pipes, wherein the thermal syphon pipes comprise first thermal syphon pipes and second thermal syphon pipes, wherein the first straight portions of the first thermal syphon pipes are respectively directly connected to the second straight portion pipes of the first thermal syphon pipes at the transition points, wherein the first straight portions of the second thermal syphon pipes are respectively connected to the second straight portions of the second thermal syphon pipes through angular portions of the second thermal syphon pipes that are connected to the first straight portions of the second thermal syphon pipes at the transition points, the transition points in the first thermal syphon pipes being at a same location along the first thermal syphon pipes as are the transition points in the second thermal syphon pipes, and wherein the angular portions of the second thermal syphon pipes extend away from the first straight portions of the second thermal syphon pipes at an angle that is greater than an angle at which the second straight portion pipes of the first thermal syphons extend away from the first straight portions of the first thermal syphon pipes.
 11. The assembly of claim 5, wherein a sum of the distance of the side surfaces between the first and second flat surfaces and respective outside diameters of embedded portions of the first straight portions that are embedded in the plate is in a range of 3.5% to 9.0% of respective lengths of the embedded portions.
 12. The assembly of claim 11, wherein the plate is rectangular, and wherein the lengths of the embedded portions are respectively greater than or equal to 80% of one of the distances on the first or the second flat surfaces that extends from one of the side surfaces into which the embedded portions are inserted to an opposite one of the side surfaces.
 13. The assembly of claim 5, wherein the second straight portions respectively extend away from the first straight portions in planes that are at an angle that is greater than the angle of the planes in which the first straight portions of the thermal syphon pipes extends from the planes along which the first and second flat surfaces extend.
 14. The assembly of claim 5, wherein the first straight portions of the first and second thermal syphon pipes are completely embedded in the channels of the plate up until the transition points of the first and second thermal syphon pipes.
 15. The assembly of claim 1, wherein the channels extend from the side surfaces through the volume of the plate toward the gravity vector at an angle between 2° to 4° from the first and second flat surfaces to positions within the volume at which the channels respectively end.
 16. The assembly of claim 1, wherein the channels extend from the side surfaces through the volume of the plate toward the gravity vector at an angle of 3° from the first and second flat surfaces to positions within the volume at which the channels respectively end.
 17. The assembly of claim 1, wherein one of the heat-generating devices is supported by and mounted on the first flat surface, and wherein another one of the heat-generating devices is supported by and mounted on the second flat surface.
 18. A two-phase syphon assembly, comprising: a plate configured to extract heat from one or more heat-generating devices in contact therewith, the plate having surfaces that define a volume thereof and one or more channels formed within the volume, the surfaces including a first flat surface, a second flat surface, and one or more side surfaces extending between the first and second flat surfaces, the first and second flat surfaces being parallel to a gravity vector, each of the flat surfaces being configured to respectively contact one of the heat-generating devices to extract heat therefrom, the channels being respectively open at the side surfaces and extending from the side surfaces through the volume of the plate toward the gravity vector to positions within the volume at which the channels respectively end; and one or more thermal syphon pipes respectively embedded within the channels and extending out of and away from the channels, the thermal syphon pipes being configured to remove the extracted heat from the plate.
 19. The assembly of claim 18, wherein the thermal syphon pipes include first and second straight portions, the first straight portions respectively including first ends of the thermal syphon pipes, the second straight portions respectively including second ends of the thermal syphon pipes, the first ends of the thermal syphon pipes being respectively embedded in the channels.
 20. The assembly of claim 19, wherein the thermal syphon pipes respectively have transition points at which the first straight portions of the thermal syphon pipes connect with other portions of the thermal syphon pipes, wherein the thermal syphon pipes comprise first thermal syphon pipes and second thermal syphon pipes, wherein the first straight portions of the first thermal syphon pipes are respectively directly connected to the second straight portion pipes of the first thermal syphon pipes at the transition points, wherein the first straight portions of the second thermal syphon pipes are respectively connected to the second straight portions of the second thermal syphon pipes through angular portions of the second thermal syphon pipes that are connected to the first straight portions of the second thermal syphon pipes at the transition points, the transition points in the first thermal syphon pipes being at a same location along the first thermal syphon pipes as are the transition points in the second thermal syphon pipes, and wherein the angular portions of the second thermal syphon pipes extend away from the first straight portions of the second thermal syphon pipes at an angle that is greater than an angle at which the second straight portion pipes of the first thermal syphons extend away from the first straight portions of the first thermal syphon pipes. 